Lex Luthor's age isn't fixed in the comics. It can change based on the creative direction of the writers and the era of the story. Generally, he's portrayed as an adult in his prime, often in his late 30s to 50s.
Well, Lex Luthor's death varies depending on the comic storyline. Sometimes it's due to his own schemes backfiring, other times it's at the hands of a powerful foe.
Lex Luthor's hair loss in the comics was often attributed to various factors. Sometimes it was a side effect of a dangerous concoction he created in his labs, or it could be linked to a confrontation with a super-powered being that had a lasting impact on his physiology.